Vasco da Gama and Zheng He both led fleets of sailing ships on multiple voyages from their home nations to India. Their motivations and political strategies were similar. They were sent on behalf of their national rulers to establish trading routes and assert dominance along those routes.
The technology that they used would have been similar as well. Their sailing ships were powered by the wind, and they would have both used similar navigational instruments, such as magnetic compasses and astrolabes, to find their way. However, in terms of culture and power, their voyages were quite different.
Vasco da Gama was a Portuguese nobleman commissioned by various Portuguese rulers to undertake his voyages on behalf of the crown. After his first trip to India, he got married and eventually had six sons. On the other hand, Zheng He was a slave of the Chinese emperor, a castrated eunuch, who eventually, through faithful service, worked his way to becoming the Grand Eunuch and then admiral of the Chinese fleet.
Both Vasco da Gama and Zheng He used military power when necessary to assert their will on the behalf of their rulers, but it seems that da Gama was much more brutal than Zheng He. One of the considerations in the use of force was certainly the size of their fleets. On da Gama's first voyage in 1497, he sailed from Portugal to India with four ships and 170 men, only fifty-four of whom made it back alive.
In contrast, Zheng He left China for India in 1405 on his first voyage with about 208 ships and 27,800 men. Obviously the presence of Zheng He and his massive fleet would have evoked much more terror and awe in the inhabitants of the places he visited.
Both men were praised as heroes after the successful completion of their voyages. Vasco da Gama died in India on his final voyage in 1524. It is not known definitively whether Zheng He died on his seventh and final voyage or whether he made it back to China and died later.